I call shenanigans on Gygax, apart from the "Why not" bit, which I think summed it up. Once you've met a creature and/or you've seen its description in the Monster Manual, you know what it freakin' is; it's no use pretending that you've done some sort of service to role-playing by bastardising legends so people don't know what they're fighting the very first time they encounter it. There was no good reason at all to call every winged horse "a Pegasus", or every snake-haired lady "a Medusa" other than possibly a lack of imagination and publication deadlines. Or watching too many of the cheesy Jason and the [Whatever] movies.
Maybe the lure to the ego of subverting classical mythology in the minds of tens of thousands of teenagers was just too much to pass up. Gygax was to mythology what Hollywood is to World War II...
Leaving aside for a moment the rest of the content of this post, including the plainly ludicrous notion that Gary Gygax may have "lacked imagination", we don't take kindly to circumventing the profanity filter. Knock it off. - Rel